Electrons are prevented from being made incident onto an insulation part of a casing between dynodes to improve a withstand voltage. The photomultiplier tube 1 is a photomultiplier tube which is provided with substrates 20, 40 arranged so as to oppose each other, with the respective opposing surfaces 20a, 40a made with an insulating material, a substrate 30 constituting a casing together with the substrates 20, 40, dynodes 31a to 31j arrayed on an opposing surface 40a on the substrate 40 so as to be spaced away sequentially from a first end side to a second end side, a photocathode 22 installed so as to be spaced away from the dynode 31a to the first end side, and an anode part 32 installed so as to be spaced away from the dynode 31j to the second end side, in which the opposing surface 20a of the substrate 20 is formed so as to cover the dynodes 31a to 31j, and a plurality of conductive layers 21a to 21j set equal in potential to dynodes 31a to 31j which are electrically independent from each other are installed at sites opposing individually the dynodes 31a to 31j on the opposing surface 20a.